Method for bleaching oils, fats, and waxes



Patented July 22,1941

UNITED STATES PA-TENT,

OFFICE METHOD non nmscnmc oms, nus, AND waxrs Anna Noder, Munich,Germany, assignor to Buffaio' Electra-Chemical Company, Inc.; Bnflalo,

No Drawing. Application June 8, 1939, Serial No. 278,168. .In GermanySeptember 6, 1937 1 Claim.

The invention refers to a method for bleaching oils, fats, and waxes. I

It has been proposed before now to bleach such products by pure hydrogenperoxide or by a mixture of hydrogen peroxide and other chemicals. Ithas also been tried to apply various organic andinorganic peroxides tothis purpose. Withsome oils, fats, and waxes relatively easy to bebleached fairly good results have indeed been obtained with this method.But there are products where by the methods known up to now nobleachingor but insuiiicient bleaching has been achieved. For such cases themethod of the present invention may mostly be applied success- I .fully.Thus with experiments of the applicant products could be bleached whereany of the methods known hitherto had failed. Thenew method has thegreat advantage that the materials bleached take a white to yellowtinge, while the other methods frequently result in giving the veryundesirable reddish tinge. Besides this 'method, when carried throughentails an automatic clearing of the oils, fats, and waxes inasmuch assuspended dirt particles are deposited at the bottom of thereaction-vessel. The chemical constants of the oils, fats and waxeschanged very inconsiderably in bleaching, consequently the typicalproperties of the respective substances are thus preserved.

The method consists in oils, fats, and waxes in liquid state beingdiluted with perpyro-phosphate, preferably sodium perpyro-phosphate,

perhaps in combination with hydrogen peroxide and other per-compounds. I

The way of procedure in carrying out this method is as follows: The fat,oil, or wax, after having been cleaned I preliminarily, if need be, inthe known manner, is heated to a temperature of 50 to 100 (7.,preferably Gil-80 C. Conveniently indirect heating is resorted to;direct heating e. g. by meahs of steam blown. in is unsuitable. Thebleaching agent is added slowly whilst stirring to the heated fat, oil,or wax. After a few hours during which the mixture is stirredcontinuously and the tempei'ature kept constant, the bleaching is ended.

It is then allowed to settle-perhaps overnightand the bleached oil, fat.or wax is withdrawn. In case of need the. bleaching may be followed by awashing according to any of the known methods. It has been found that insome cases the intensity of the bleaching may even be, in-

. creased by using instead of perpyro-phosphate a mixture ofperpyro-phosphate and hydrogen peroxide or other per-compounds e. g.benzoyl peroxide. Then one proceeds conveniently adding first thepemyro-phosphate-and subsequently the other per-compounds.

' I Example I showed the following values:

Raw Bleached Number of iodine 52.0 no Number of saponiflcation 212 214Comparative tests with pure hydrogen peroxide and with bennoyl peromdeplus hydrogen peroxide showed a considerably lesser bleaching action.With pure hydrogen peroxide bleaching a very undesirable reddish tintappeared. A

Example If (a) 100 kilos of cotton oil (cotton seed oil) were first ofall cleaned preliminarily with 5% trinatrium phosphate solution at 80 C.Thereupon the goods were bleached with 2% sodium p'erpyrophosphate forthree hours at -'75 C. whilst stirring.

(b) 100 kilos of cotton 011 (cotton seed oil) were treated preliminarilyas described above. As

ableaching agent served 1% of perpyro-phosphate and 1% of hydrogenperoxide (30%). The goods were likewise bleached at IO- C. for threehours. The originally opaque, blackbrown coloured oil was completelyclear in both cases and took a light-yellow tint. The numbers ofanalysis wer as follows:

Raw Bleached Numbe'roflodlne .l 103.0 103.0 Numbcrofsaponifleation 179.2177,0

Example III v stirring with a mixture or 4% sodium perpyro-- phosphateand 3% hydrogen peroxide (30%).

Then the sample was allowed to settle overnight at '80? 0. Then it waswashed with diluted sulphuric acid and water. After bleaching, theoriginally dark, yellow wax had acquired a white, slightly yellowishtinge. The bleaching tint could still be improved somewhat by using 4%of sodium perpyro-phosphate, 3% or hydrogen peroxide (30%) and 2% 01'benzoyl peroxide as a bleaching agent.

Comparative tests with an equal amount or active oxygen in the form orpure H2O: or H2O:

plus benzoyl .peroxide produced a worse result. 2

The numbers oi analysis'were as follows:

Raw Bleached Number oi saponifloation s2. 4 80. 9

What I claim is: a

The method of bleaching a material of the group consisting of oils, fatsand waxes which comprises subjecting the material to indirect heating toraise the temperature thereof to 50 C.

to 100 C. and thereafter slowly adding to the

